GZIPFilter.java Source code

Introduction

Here is the source code for GZIPFilter.java

Source

/*
 * Copyright 2003 Jayson Falkner (jayson@jspinsider.com)
 * This code is from "Servlets and JavaServer pages; the J2EE Web Tier",
 * http://www.jspbook.com. You may freely use the code both commercially
 * and non-commercially. If you like the code, please pick up a copy of
 * the book and help support the authors, development of more free code,
 * and the JSP/Servlet/J2EE community.
 */

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.zip.GZIPOutputStream;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;

public class GZIPFilter implements Filter {

    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
            throws IOException, ServletException {
        if (req instanceof HttpServletRequest) {
            HttpServletRequest request = (HttpServletRequest) req;
            HttpServletResponse response = (HttpServletResponse) res;
            String ae = request.getHeader("accept-encoding");
            if (ae != null && ae.indexOf("gzip") != -1) {
                GZIPResponseWrapper wrappedResponse = new GZIPResponseWrapper(response);
                chain.doFilter(req, wrappedResponse);
                wrappedResponse.finishResponse();
                return;
            }
            chain.doFilter(req, res);
        }
    }

    public void init(FilterConfig filterConfig) {
        // noop
    }

    public void destroy() {
        // noop
    }
}

/*
 * Copyright 2003 Jayson Falkner (jayson@jspinsider.com)
 * This code is from "Servlets and JavaServer pages; the J2EE Web Tier",
 * http://www.jspbook.com. You may freely use the code both commercially
 * and non-commercially. If you like the code, please pick up a copy of
 * the book and help support the authors, development of more free code,
 * and the JSP/Servlet/J2EE community.
 */
class GZIPResponseStream extends ServletOutputStream {
    protected ByteArrayOutputStream baos = null;
    protected GZIPOutputStream gzipstream = null;
    protected boolean closed = false;
    protected HttpServletResponse response = null;
    protected ServletOutputStream output = null;

    public GZIPResponseStream(HttpServletResponse response) throws IOException {
        super();
        closed = false;
        this.response = response;
        this.output = response.getOutputStream();
        baos = new ByteArrayOutputStream();
        gzipstream = new GZIPOutputStream(baos);
    }

    public void close() throws IOException {
        if (closed) {
            throw new IOException("This output stream has already been closed");
        }
        gzipstream.finish();

        byte[] bytes = baos.toByteArray();

        response.addHeader("Content-Length", Integer.toString(bytes.length));
        response.addHeader("Content-Encoding", "gzip");
        output.write(bytes);
        output.flush();
        output.close();
        closed = true;
    }

    public void flush() throws IOException {
        if (closed) {
            throw new IOException("Cannot flush a closed output stream");
        }
        gzipstream.flush();
    }

    public void write(int b) throws IOException {
        if (closed) {
            throw new IOException("Cannot write to a closed output stream");
        }
        gzipstream.write((byte) b);
    }

    public void write(byte b[]) throws IOException {
        write(b, 0, b.length);
    }

    public void write(byte b[], int off, int len) throws IOException {
        if (closed) {
            throw new IOException("Cannot write to a closed output stream");
        }
        gzipstream.write(b, off, len);
    }

    public boolean closed() {
        return (this.closed);
    }

    public void reset() {
        //noop
    }
}

/*
 * Copyright 2003 Jayson Falkner (jayson@jspinsider.com)
 * This code is from "Servlets and JavaServer pages; the J2EE Web Tier",
 * http://www.jspbook.com. You may freely use the code both commercially
 * and non-commercially. If you like the code, please pick up a copy of
 * the book and help support the authors, development of more free code,
 * and the JSP/Servlet/J2EE community.
 */
class GZIPResponseWrapper extends HttpServletResponseWrapper {
    protected HttpServletResponse origResponse = null;
    protected ServletOutputStream stream = null;
    protected PrintWriter writer = null;

    public GZIPResponseWrapper(HttpServletResponse response) {
        super(response);
        origResponse = response;
    }

    public ServletOutputStream createOutputStream() throws IOException {
        return (new GZIPResponseStream(origResponse));
    }

    public void finishResponse() {
        try {
            if (writer != null) {
                writer.close();
            } else {
                if (stream != null) {
                    stream.close();
                }
            }
        } catch (IOException e) {
        }
    }

    public void flushBuffer() throws IOException {
        stream.flush();
    }

    public ServletOutputStream getOutputStream() throws IOException {
        if (writer != null) {
            throw new IllegalStateException("getWriter() has already been called!");
        }

        if (stream == null)
            stream = createOutputStream();
        return (stream);
    }

    public PrintWriter getWriter() throws IOException {
        if (writer != null) {
            return (writer);
        }

        if (stream != null) {
            throw new IllegalStateException("getOutputStream() has already been called!");
        }

        stream = createOutputStream();
        writer = new PrintWriter(new OutputStreamWriter(stream, "UTF-8"));
        return (writer);
    }

    public void setContentLength(int length) {
    }
}